Piezoelectric material, piezoelectric element, method for manufacturing piezoelectric element, and electronic device

ABSTRACT

The present invention can provide a lead-free piezoelectric material having a high piezoelectric constant in the room temperature range. The present invention for this purpose is a piezoelectric material including a main component containing a perovskite metal oxide represented by following general formula (1),
 
Ba a (Ti 1-x Zr x )O 3   (1)
 
where 0.02≤x≤0.13 and 0.986≤a≤1.02, a first auxiliary component containing Mn, and a second auxiliary component containing trivalent Bi, wherein an amount of the contained Mn is 0.0020 moles or more and 0.0150 moles or less relative to 1 mole of the metal oxide, and an amount of the contained Bi is 0.00042 moles or more and 0.00850 moles or less relative to 1 mole of the metal oxide.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a piezoelectric material, and inparticular, relates to a lead-free piezoelectric material, which doesnot contain lead. The present invention also relates to a piezoelectricelement, a multilayered piezoelectric element, a liquid discharge head,a liquid discharge apparatus, an ultrasonic motor, an optical device, anoscillatory device, a dust removing device, an imaging apparatus, and anelectronic device that use the piezoelectric material, and a method formanufacturing the piezoelectric element.

Description of the Related Art

Generally, a piezoelectric material is an ABO₃-type perovskite metaloxide such as lead zirconium titanate (hereinafter referred to as“PZT”). PZT, however, contains lead as an A-site element, and therefore,the environmental impact of PZT is regarded as a problem. Thus, there isa need for a piezoelectric material using a perovskite metal oxide thatdoes not contain lead.

As a piezoelectric material using a perovskite metal oxide that does notcontain lead, barium titanate is known. Further, to improve theproperties of the piezoelectric material, a material is developed basedon the composition of barium titanate.

Japanese Patent Application Laid-Open No. 11-060334 discusses a materialof which the piezoelectric properties (the piezoelectric constant) areimproved by replacing a part of the B site of barium titanate with Zr toraise a phase transition temperature T_(to) to the room temperaturerange, and using a local maximum in the dielectric constant due to aphase transition.

To drive a high-power actuator, however, if room temperature is set to25° C. and the room temperature range is set to, for example, 20° C. to30° C., the piezoelectric properties of the piezoelectric materialdiscussed in Japanese Patent Application Laid-Open No. 11-060334 are notsufficient within the room temperature range. Generally, thepiezoelectric properties (the piezoelectric constant) increase near thephase transition temperature. In the case of the piezoelectric materialdiscussed in Japanese Patent Application Laid-Open No. 11-060334, evenif the amount of contained Zr is adjusted to shift the phase transitiontemperature of the piezoelectric material to near room temperature, thepiezoelectric properties are still insufficient.

SUMMARY OF THE INVENTION

Aspects of the present invention are directed to a lead-freepiezoelectric material having more excellent piezoelectric propertieswhen the phase transition temperature T_(to) is in the room temperaturerange.

According to an aspect of the present invention, a piezoelectricmaterial includes a main component containing a perovskite metal oxiderepresented by following general formula (1),Ba_(a)(Ti_(1-x)Zr_(x))O₃  (1)where 0.02≤x≤0.13 and 0.986≤a≤1.02a first auxiliary component containing Mn, and a second auxiliarycomponent containing trivalent Bi, wherein an amount of the contained Mnis 0.0020 moles or more and 0.0150 moles or less relative to 1 mole ofthe metal oxide, and an amount of the contained Bi is 0.00042 moles ormore and 0.00850 moles or less relative to 1 mole of the metal oxide.

In the above piezoelectric material, a tetragonal-orthorhombic phasetransition temperature T_(to) is 10° C. or more.

According to another aspect of the present invention, a piezoelectricelement includes at least a first electrode, a piezoelectric materialportion, and a second electrode, wherein a piezoelectric materialforming the piezoelectric material portion is the above piezoelectricmaterial.

According to yet another aspect of the present invention, a method formanufacturing a piezoelectric element includes providing thepiezoelectric material with a first electrode and a second electrode,applying a voltage at a temperature at which the piezoelectric materialbecomes tetragonal, and cooling the piezoelectric material to atemperature at which the piezoelectric material becomes orthorhombic,while retaining the voltage.

According to yet another aspect of the present invention, a multilayeredpiezoelectric element includes a plurality of piezoelectric materiallayers and a plurality of electrode layers including an internalelectrode, the piezoelectric material layers and the electrode layersbeing alternately stacked, wherein a piezoelectric material is the abovepiezoelectric material.

According to yet another aspect of the present invention, a liquiddischarge head includes at least a liquid chamber including a vibratingunit provided with the above piezoelectric element or the abovemultilayered piezoelectric element, and a discharge port communicatingwith the liquid chamber.

According to yet another aspect of the present invention, a liquiddischarge apparatus includes a stage for an object, and the above liquiddischarge head.

According to yet another aspect of the present invention, an ultrasonicmotor includes at least a vibrating member provided with the abovepiezoelectric element or the above multilayered piezoelectric element,and a moving member in contact with the vibrating member.

According to yet another aspect of the present invention, an opticaldevice includes a driving unit provided with the above ultrasonic motor.

According to yet another aspect of the present invention, an oscillatorydevice includes a vibrating member including a diaphragm provided withthe above piezoelectric element or the above multilayered piezoelectricelement.

According to yet another aspect of the present invention, a dustremoving device includes a vibrating unit provided with the aboveoscillatory device.

According to yet another aspect of the present invention, an imagingapparatus includes at least the above dust removing device, and an imagesensor unit, wherein the diaphragm of the dust removing device isprovided on a light-receiving surface side of the image sensor unit.

According to yet another aspect of the present invention, an electronicdevice includes a piezoelectric acoustic component provided with theabove piezoelectric element or the above multilayered piezoelectricelement.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration of apiezoelectric element according to an exemplary embodiment of thepresent invention.

FIGS. 2A and 2B are schematic cross-sectional views each illustrating aconfiguration of a multilayered piezoelectric element according to anexemplary embodiment of the present invention.

FIGS. 3A and 3B are schematic diagrams illustrating a configuration of aliquid discharge head according to an exemplary embodiment of thepresent invention.

FIG. 4 is a schematic diagram illustrating a liquid discharge apparatusaccording to an exemplary embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating the liquid dischargeapparatus according to the exemplary embodiment of the presentinvention.

FIGS. 6A and 6B are schematic diagrams illustrating a configuration ofan ultrasonic motor according to an exemplary embodiment of the presentinvention.

FIGS. 7A and 7B are schematic diagrams illustrating an optical deviceaccording to an exemplary embodiment of the present invention.

FIG. 8 is a schematic diagram illustrating an optical device accordingto an exemplary embodiment of the present invention.

FIGS. 9A and 9B are schematic diagrams illustrating a case where anoscillatory device according to an exemplary embodiment of the presentinvention is used as a dust removing device.

FIGS. 10A to 10C are schematic diagrams illustrating a configuration ofa piezoelectric element in a dust removing device according to anexemplary embodiment of the present invention.

FIGS. 11A and 11B are schematic diagrams illustrating an oscillationprinciple of a dust removing device according to an exemplary embodimentof the present invention.

FIG. 12 is a schematic diagram illustrating an imaging apparatusaccording to an exemplary embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating an imaging apparatusaccording to an exemplary embodiment of the present invention.

FIG. 14 is a schematic diagram illustrating an electronic deviceaccording to an exemplary embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments for carrying out the present invention will bedescribed below.

A piezoelectric material according to the present invention is apiezoelectric material including a main component containing aperovskite metal oxide represented by the following general formula (1),a first auxiliary component containing Mn, and a second auxiliarycomponent containing trivalent Bi. Further, the amount of the containedMn is 0.0020 moles or more and 0.0150 moles or less relative to 1 moleof the metal oxide, and the amount of the contained Bi is 0.00042 molesor more and 0.00850 moles or less relative to 1 mole of the metal oxide.Ba_(a)(Ti_(1-x)Zr_(x))O₃  (1)(where 0.02≤x≤0.13 and 0.986≤a≤1.02)(Perovskite Metal Oxide)

In the present invention, a “perovskite metal oxide” refers to a metaloxide having a perovskite structure, which is ideally a cubic structure,as discussed in the fifth edition of Iwanami Rikagaku Jiten (issued onFeb. 20, 1998 by Iwanami Shoten, Publishers). Generally, a metal oxidehaving a perovskite structure is represented by a chemical formula ABO₃.In the perovskite metal oxide, the elements A and B in the forms of ionsoccupy particular unit cell positions termed an A site and a B site,respectively. For example, in a cubic structure unit cell, the element Aoccupies the vertices of the cube, and the element B occupies thebody-centered position of the cube. The element O occupies theface-centered positions of the cube as anions of oxygen.

In the metal oxide represented by the general formula (1), a metallicelement positioned at the A site is Ba, and metallic elements positionedat the B site are Ti and Zr. A part of Ba, however, may be positioned atthe B site. Similarly, a part of Ti and Zr may be positioned at the Asite.

In the general formula (1), the molar ratio of the B-site elements tothe element O is 1:3. However, even if the ratio of the amounts of theelements slightly deviates from the above molar ratio, such a deviatingratio is included in the scope of the present invention so long as themain phase of the metal oxide is a perovskite structure.

It is possible to determine that the metal oxide has a perovskitestructure, for example, by a structure analysis using X-ray diffractionor electron diffraction. If the main phase of the metal oxide is aperovskite structure, a large portion of the results of the structureanalysis is made up of analysis data derived from the perovskitestructure.

(Main Component of Piezoelectric Material)

In the piezoelectric material according to the present invention, in thegeneral formula (1), “a” indicating the ratio of the molar amount of Baat the A site to the molar amount of Ti and Zr at the B site is in therange of 0.9860≤a≤1.0200.

The piezoelectric material contains preferably 90 mole percent or more,and more preferably 95 mole percent or more, of the perovskite metaloxide represented by the general formula (1), as the main component.

If “a” is smaller than 0.9860, abnormal grain growth is likely to occurin the crystal grains forming the piezoelectric material, and themechanical strength of the material decreases. If, on the other hand,“a” is greater than 1.0200, the temperature required for grain growth istoo high. Thus, the piezoelectric material cannot be sintered in ageneral burning furnace. Here, “the piezoelectric material cannot besintered” means that the density does not reach a sufficient value, ormany pores and defects are present in the piezoelectric material.

In the general formula (1), “x” indicating the molar proportion of Zr atthe B site is in the range of 0.02≤x≤0.13. If “x” is greater than 0.13,the Curie temperature is too low, and the high-temperature durability isnot sufficient. If “x” is smaller than 0.02, sufficient piezoelectricproperties are not obtained in the temperature range for driving thedevice (−30° C. to 50° C.)

In the specification, the “Curie temperature (T_(c))” refers to thetemperature at which the ferroelectricity of the material disappears.Normally, the piezoelectric properties of the piezoelectric materialalso disappear at the Curie temperature T_(c) or above. Examples of themethod for measuring the Curie temperature T_(c) include a method fordirectly measuring the temperature at which the ferroelectricitydisappears, while changing the measurement temperature, and a method formeasuring the relative dielectric constant while changing themeasurement temperature using a minute alternating electric field,thereby obtaining the Curie temperature T_(c) from the temperature atwhich the relative dielectric constant indicates a local maximum.

The method for measuring the composition of the piezoelectric materialaccording to the present invention is not particularly limited. Examplesof the method include an X-ray fluorescence analysis (XRF), aninductively coupled plasma (ICP) emission spectroscopic analysis, and anatomic absorption spectrometry. Any of the methods can calculate theweight ratio and the composition ratio of the elements contained in thepiezoelectric material.

(First Auxiliary Component of Piezoelectric Material)

The first auxiliary component contains Mn. The amount of the containedMn is 0.0020 moles or more and 0.0150 moles or less relative to 1 moleof the perovskite metal oxide.

At this time, the amounts of the contained auxiliary components areobtained as follows. First, the amounts of metals contained in thepiezoelectric material measured using an XRF, an ICP emissionspectroscopic analysis, or an atomic absorption spectrometry arecalculated. Then, based on the amounts of the contained metals, theelements forming the metal oxide represented by the general formula (1)are converted into moles and represented by the ratio of the moles ofthe elements to the moles of the auxiliary components with the totalmoles of the elements being 1.

If the piezoelectric material according to the present inventioncontains Mn in the above range, the mechanical quality factor of thepiezoelectric material improves in the room temperature range. The“mechanical quality factor” refers to a factor representing elastic losscaused by an oscillation when the piezoelectric material is evaluated asan oscillator, and the value of the mechanical quality factor isobserved as the sharpness of a resonance curve in an impedancemeasurement. That is, the mechanical quality factor is a constantrepresenting the sharpness of the resonance of the oscillator. Thehigher the mechanical quality factor is, the less the energy is lost byan oscillation. A high insulation properties and a high mechanicalquality factor ensure long-term reliability of a piezoelectric elementwhen a piezoelectric element including the piezoelectric material isdriven by application of a voltage.

If the amount of the contained Mn is less than 0.0020 moles, themechanical quality factor is small, namely less than 150, in the roomtemperature range. If the mechanical quality factor is small, when apiezoelectric element including the piezoelectric material and a pair ofelectrodes is driven as a resonance device, the power consumptionincreases. The mechanical quality factor is preferably 200 or more, andmore preferably 400 or more. The mechanical quality factor is even morepreferably 700 or more. In this range, the power consumption does notextremely increase when the device is driven. If, on the other hand, theamount of the contained Mn is greater than 0.0150 moles, the insulationproperties of the piezoelectric material decrease. For example, thedielectric loss tangent, at a frequency of 1 kHz, of the piezoelectricmaterial may exceed 0.006, or the resistivity of the piezoelectricmaterial may fall below 1 GΩ cm. The dielectric loss tangent can bemeasured using an impedance analyzer. If the dielectric loss tangent is0.006 or less, it is possible to, even when a high voltage is applied tothe piezoelectric material used as an element, obtain a stable operationof the element. If the resistivity of the piezoelectric material is atleast 1 GΩ cm, the piezoelectric material can be polarized and driven asa piezoelectric element. The resistivity is more preferably 50 GΩ cm ormore.

The Mn is not limited to metallic Mn, and is only required to becontained as an Mn component in the piezoelectric material. The form ofcontaining the Mn does not matter. For example, the Mn may be dissolvedin the B site, or may be contained at grain boundaries. Alternatively,an Mn component in the form of a metal, an ion, an oxide, a metallicsalt, or a complex may be contained in the piezoelectric material. It ismore desirable that Mn should be present in terms of insulationproperties and ease of sintering. Generally, the valence of Mn can take4+, 2+, and 3+. If a conduction electron is present in a crystal (forexample, if an oxygen defect is present in a crystal, or if a donorelement occupies the A site), the valence of Mn decreases, for example,from 4+ to 3+ or 2+, thereby trapping the conduction electron. This canimprove the insulation resistance.

If, on the other hand, the valence of Mn is lower than 4+, such as 2+,the Mn serves as an acceptor. If Mn is present as an acceptor in aperovskite structure crystal, a hole is generated in the crystal, or anoxygen vacancy is formed in the crystal.

If the valence of a large amount of added Mn is 2+ or 3+, theintroduction of an oxygen vacancy alone cannot completely compensate fora hole, and the insulation resistance decreases. Thus, it is desirablethat the valence of the majority of the Mn should be 4+. However, anextremely small amount of the Mn may have a valence lower than 4+,occupy the B site of the perovskite structure as an acceptor, and forman oxygen vacancy. This is because the Mn having a valence of 2+ or 3+and the oxygen vacancy form a defect dipole and the mechanical qualityfactor of the piezoelectric material can be thereby improved. Iftrivalent Bi occupies the A site, Mn is likely to take a valence lowerthan 4+ to achieve a charge balance.

The valence of a minute amount of Mn added to a nonmagnetic(diamagnetic) material can be evaluated by measuring the temperaturedependence of the magnetic susceptibility. The magnetic susceptibilitycan be measured by a superconducting quantum interference device(SQUID), a vibrating sample magnetometer (VSM), or a magnetic balance.Generally, a magnetic susceptibility χ obtained by the measurementfollows the Curie-Weiss law represented by formula 2.χ=C/(T−θ)  (Formula 2)(C: the Curie constant, θ: the paramagnetic Curie temperature)

Generally, a minute amount of Mn added to a nonmagnetic materialindicates spin S=5/2 if the valence is 2+, S=2 if the valence is 3+, andS=3/2 if the valence is 4+. Thus, the Curie constant C per unit amountof Mn is a value corresponding to the value of the spin S with eachvalence of the Mn. Thus, the Curie constant C is derived from thetemperature dependence of the magnetic susceptibility χ, whereby theaverage valence of Mn in a sample can be evaluated.

To evaluate the Curie constant C, it is desirable to measure thetemperature dependence of the magnetic susceptibility from the lowestpossible temperature. This is because the amount of Mn is minute, andtherefore, the value of the magnetic susceptibility is also very smallat a relatively high temperature such as at around room temperature.Thus, it is difficult to measure the temperature dependence. The Curieconstant C can be derived from the slope of the straight line obtainedby plotting a multiplicative inverse 1/χ of the magnetic susceptibilitywith respect to a temperature T and linearly approximating the plottedpoints.

(Second Auxiliary Component of Piezoelectric Material)

The second auxiliary component contains Bi. The amount of the containedBi is 0.00042 moles or more and 0.00850 moles or less relative to 1 moleof the metal oxide.

If the piezoelectric material according to the present inventioncontains Bi in the above range, it is considered that a large portion ofthe trivalent Bi is positioned at the A site, and a portion of thetrivalent Bi is positioned at crystal grain boundaries. If the Bi ispositioned at the A site, a tetragonal-orthorhombic phase transitiontemperature T_(to) shifts to a low temperature. This is an actionopposite to that caused by the piezoelectric material containing Zr.

Based on the above, although there has been conventionally an upperlimit on the amount of Zr required to locate the phase transitiontemperature T_(to) near room temperature, the addition of Zr togetherwith Bi enables the piezoelectric material to contain more Zr.

Generally, the Curie temperature and the piezoelectric properties (thepiezoelectric constant) of a piezoelectric material tend to have atrade-off relationship. The effect of the trade-off relationship is asfollows. If the amount of Zr contained in the piezoelectric materialincreases, the Curie temperature T_(c) becomes lower than that of purebarium titanate, which does not contain Zr. This improves thepiezoelectric properties.

Thus, in the case of piezoelectric materials having the phase transitiontemperatures T_(to) near the same room temperature, the piezoelectricmaterial containing Bi can contain more Zr than the piezoelectricmaterial that does not contain Bi. Consequently, the piezoelectricmaterial containing Bi has excellent piezoelectric properties near roomtemperature.

If the amount of the contained Bi is smaller than 0.00042 moles, toimprove the piezoelectric properties, the amount of Zr in the materialcontaining the Bi is reduced with a view to bringing the phasetransition temperature T_(to) close to room temperature. However, such amaterial containing a small amount of Zr has a high Curie temperatureT_(c) and a low dielectric constant. Thus, the piezoelectric propertiesnear room temperature are small.

If, on the other hand, the amount of the contained Bi is greater than0.00850 moles, the solubility limit of Bi in the above perovskite metaloxide is exceeded. Thus, the piezoelectric properties are not sufficientdue to the remaining Bi, which is not desirable. In terms of obtainingmore desirable mechanical quality factor and piezoelectric constant inthe room temperature range, the amount of the contained Bi is morepreferably 0.0020 moles or more and 0.00850 moles or less.

The Bi as the second auxiliary component is not limited to metallic Bi,and is only required to be contained as a Bi component in thepiezoelectric material. The form of containing the Bi does not matter.It is, however, desirable that the Bi as the second auxiliary componentshould be dissolved as trivalent Bi in the A site. The valence of the Bican be identified by the X-ray absorption fine structure (XAFS)measurement using radiation light.

(Third Auxiliary Component of Piezoelectric Material)

It is desirable that the piezoelectric material according to the presentinvention should include a third auxiliary component containing at leastone of Si and B. The amount of the contained third auxiliary componentis preferably 0.001 parts by weight or more and 4.000 parts by weight orless, and more preferably 0.003 parts by weight or more and 2.000 partsby weight or less, in terms of metal relative to 100 parts by weight ofthe perovskite metal oxide represented by the general formula (1).

The third auxiliary component contains at least one of Si and B. B andSi are segregated at the grain boundaries of the piezoelectric material.This reduces a leakage current flowing through the grain boundaries, andtherefore increases the resistivity. If the piezoelectric materialcontains 0.001 or more parts by weight of the third auxiliary component,the resistivity becomes high, and the insulation properties improve,which is desirable. If the piezoelectric material contains more than4.000 parts by weight of the third auxiliary component, the dielectricconstant decreases, and as a result, the piezoelectric propertiesdecrease, which is not desirable. The amount of the contained Si is morepreferably 0.003 parts by weight or more and 1.000 parts by weight orless relative to 100 parts by weight of the perovskite metal oxide. Theamount of the contained B is more preferably 0.001 parts by weight ormore and 1.000 parts by weight or less.

A multilayered piezoelectric element includes a thin piezoelectricmaterial between electrodes, and therefore needs to have durability to ahigh electric field. Thus, the piezoelectric material according to thepresent invention excels particularly in its insulation properties, andtherefore can be suitably used for a multilayered piezoelectric element.

The piezoelectric material according to the present invention maycontain a certain amount of Nb contained as an unavoidable component ina commercial raw material of Ti and a certain amount of Hf contained asan unavoidable component in a commercial raw material of Zr.

The piezoelectric material according to the present invention containsthe perovskite metal oxide represented by the general formula (1), thefirst auxiliary component, the second auxiliary component, and the thirdauxiliary component preferably in 98.5 mole percent or more in total. Asdescribed above, the piezoelectric material contains, as the maincomponent, the perovskite metal oxide represented by the general formula(1) preferably in 90 mole percent or more, and more preferably in 95mole percent or more.

(Regarding Grain Diameter and Equivalent Circular Diameter of CrystalGrain)

The average equivalent circular diameter of the crystal grains formingthe piezoelectric material according to the present invention ispreferably 500 nm or more and 10 μm or less. The “average equivalentcircular diameter” refers to the average value of the equivalentcircular diameters of a plurality of crystal grains. The averageequivalent circular diameter of the crystal grains is in this range,whereby the piezoelectric material according to the present inventioncan have excellent piezoelectric properties and mechanical strength. Ifthe average equivalent circular diameter is less than 500 nm, thepiezoelectric properties may not be sufficient. If, on the other hand,the average equivalent circular diameter is greater than 10 μm, themechanical strength may decrease. The range of the average equivalentcircular diameter is more preferably 500 nm or more and 4.5 μm or less.

An “equivalent circular diameter” in the present invention represents a“projected area equivalent circular diameter” generally termed in amicroscopic observation method and represents the diameter of a truecircle having the same area as the projected area of a crystal grain. Inthe present invention, the method for measuring the equivalent circulardiameter is not particularly limited. The equivalent circular diametercan be obtained by, for example, performing image processing on aphotographic image obtained by photographing the surface of thepiezoelectric material using a polarizing microscope or a scanningelectron microscope (SEM). The optimal magnification varies depending onthe target grain diameter. Thus, either an optical microscope or anelectron microscope may be appropriately used. The equivalent circulardiameter may be obtained not from an image of the surface of thematerial but from an image of a polished surface or a cross section ofthe material.

(Regarding Relative Density)

The relative density of the piezoelectric material according to thepresent invention is preferably 93% or more and 100% or less.

The relative density is the proportion of the theoretical densitycalculated from the lattice constant of the piezoelectric material andthe atomic weights of the constituent elements of the piezoelectricmaterial, to the actually measured density. The lattice constant can bemeasured by, for example, an X-ray diffraction analysis. The density canbe measured by, for example, the Archimedes' principle.

If the relative density is smaller than 93%, the piezoelectricproperties or the mechanical quality factor may not be sufficient, orthe mechanical strength may decrease.

The relative density of the piezoelectric material according to thepresent invention is more preferably in the range of 95% or more and100% or less, and even more preferably in the range of 97% or more and100% or less.

(Regarding Dielectric Loss Tangent)

The dielectric loss tangent, at a frequency of 1 kHz, of thepiezoelectric material according to the present invention is preferably0.006 or less. The dielectric loss tangent can be measured by applyingan alternating electric field having a frequency of 1 kHz and anelectric field strength of 10 V/cm, using a commercial impedanceanalyzer.

(Form of Piezoelectric Material)

The form of the piezoelectric material according to the presentinvention is not limited. The form may be any of a ceramic, powder, asingle crystal, and slurry, but is preferably a ceramic. In thespecification, the term “ceramic” represents an aggregate (also referredto as a “bulk body”) of crystal grains containing a metal oxide as abasic component and produced by baking through heat treatment, that is,represents a so-called polycrystal. The ceramic includes productsprocessed after sintering.

(Method for Manufacturing Piezoelectric Material)

The method for manufacturing the piezoelectric material according to thepresent invention is not particularly limited. A typical manufacturingmethod is described below.

(Raw Materials of Piezoelectric Material)

When the piezoelectric material is manufactured, it is possible toemploy a general technique for producing a compact from a solid powderof an oxide, a carbonate, a nitrate, an oxalate, or an acetate thatcontains constituent elements, and sintering the compact under normalpressure. The raw materials of the piezoelectric material include metalcompounds such as a Ba compound, a Ti compound, a Zr compound, an Mncompound, a Bi compound, a B compound, and an Si compound.

Examples of the Ba compound that can be used include barium oxide,barium carbonate, barium oxalate, barium acetate, barium nitrate, bariumtitanate, and barium zirconate. It is desirable to use a commerciallyavailable high-purity type (for example, a purity of 99.99% or more) ofeach of the Ba compounds.

Examples of the Ti compound that can be used include titanium oxide,barium titanate, and barium zirconate titanate. If an alkaline earthmetal such as barium is contained in each of the Ti compounds, it isdesirable to use a commercially available high-purity type (e.g., apurity of 99.99% or more) of the Ti compound.

Examples of the Zr compound that can be used include zirconium oxide,barium zirconate, and barium zirconate titanate. If an alkaline earthmetal such as barium is contained in each of the Zr compounds, it isdesirable to use a commercially available high-purity type (e.g., apurity of 99.99% or more) of the Zr compound.

Examples of the Mn compound that can be used include manganesecarbonate, manganese oxide, manganese dioxide, manganese acetate, andtrimanganese tetroxide.

Examples of the Bi compound that can be used include bismuth oxide.

Examples of the Si compound that can be used include silicon dioxide.

Examples of the B compound that can be used include boron oxide.

Further, in the piezoelectric material according to the presentinvention, a raw material for adjusting “a” indicating the ratio of theabundance of Ba at the A site to the molar amount of Ti and Zr at the Bsite is not particularly limited. Any of a Ba compound, a Ti compound,and a Zr compound has the same effect.

(Granulated Powder and Compact)

The compact is a solid obtained by shaping the solid powder. Examples ofthe shaping method include uniaxial pressing, cold isostatic pressing,warm isostatic pressing, casting, and extrusion molding. When thecompact is prepared, it is desirable to use a granulated powder. Thesintering of the compact using a granulated powder has the advantagethat the distribution of the sizes of the crystal grains of the sinteredbody is likely to become uniform. Further, in terms of increasing theinsulation properties of the sintered body, it is desirable that thecompact should include the third auxiliary component containing at leastone of Si and B.

The method for granulating the raw material powder of the piezoelectricmaterial is not particularly limited. In terms of the ability to makethe grain diameters of the granulated powder more uniform, it is mostdesirable to use spray drying as the granulating method.

Examples of a binder that can be used to granulate the raw materialpowder include polyvinyl alcohol (PVA), polyvinyl butyral (PVB), and anacrylic resin. The amount of the binder to be added is preferably 1 partby weight or more and 10 parts by weight or less relative to 100 partsby weight of the raw material powder of the piezoelectric material, andis more preferably 2 parts by weight or more and 5 parts by weight orless, in terms of increasing the density of the compact.

(Sintering)

The method for sintering the compact is not particularly limited.

Examples of the sintering method include sintering in an electricfurnace, sintering in a gas furnace, electrical heating, microwavesintering, millimeter wave sintering, and hot isostatic pressing (HIP).The sintering in an electric furnace or a gas furnace may use acontinuous furnace or a batch furnace.

The sintering temperature in the sintering method is not particularlylimited. It is desirable that the sintering temperature should be thetemperature that allows each compound to react and crystals tosufficiently grow. In terms of limiting the grain diameters in the rangeof 500 nm to 10 μm, the sintering temperature is preferably 1100° C. ormore and 1300° C. or less, and more preferably 1100° C. or more and1250° C. or less. The piezoelectric material sintered in the abovetemperature range demonstrates excellent piezoelectric performance. Tostably reproduce the properties of the piezoelectric material obtainedby the sintering process, the sintering process may be performed for 2hours or more and 48 hours or less with the sintering temperature heldconstant in the above range. Further, a sintering method such astwo-stage sintering may also be used. In view of productivity, however,it is desirable to use a method that does not involve a rapidtemperature change.

It is desirable to polish the piezoelectric material obtained by thesintering process and then heat-treat the piezoelectric material at atemperature of 1000° C. or above. If the piezoelectric material ismechanically polished, a residual stress occurs within the piezoelectricmaterial. The residual stress, however, is alleviated by heat-treatingthe piezoelectric material at 1000° C. or above. This makes thepiezoelectric properties of the piezoelectric material more excellent.Further, the heat treatment also has the effect of removing the rawmaterial powder of barium carbonate precipitated in grain boundaryportions, or the like. The time of the heat treatment is notparticularly limited, but is preferably an hour or more.

(Piezoelectric Element)

FIG. 1 is a schematic diagram illustrating the configuration of apiezoelectric element according to an exemplary embodiment of thepresent invention. The piezoelectric element according to the presentinvention is a piezoelectric element including at least a firstelectrode 1, a piezoelectric material portion 2, and a second electrode3. The piezoelectric material portion 2 is the piezoelectric materialaccording to the present invention.

The piezoelectric properties of the piezoelectric material according tothe present invention can be evaluated by applying the piezoelectricmaterial to a piezoelectric element including at least a first electrodeand a second electrode. Each of the first and second electrodes isformed of a conductive layer having a thickness of about 5 nm to 10 μm.The material of the electrode is not particularly limited, and may be amaterial normally used for a piezoelectric element. Examples of thematerial include metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe,Cr, Ni, Pd, Ag, and Cu, alloys of these, and compounds of these.

Each of the first and second electrodes may contain one of these, or maybe formed by stacking two or more of these. Further, the first andsecond electrodes may be different in material from each other.

The method for manufacturing the first and second electrodes is notlimited. Each electrode may be formed by baking of a metal paste, or maybe formed by sputtering or vapor deposition. Further, both the first andsecond electrodes may be patterned into desired shapes for use.

(Polarization Treatment)

It is more desirable that the spontaneous polarization axes of thepiezoelectric element should be aligned in a certain direction. If thespontaneous polarization axes are aligned in a certain direction, thepiezoelectric constant of the piezoelectric element becomes large.

The method for polarizing the piezoelectric element is not particularlylimited. The polarization treatment may be performed in the atmosphereor in silicone oil. The temperature for the polarization is preferably atemperature at which the piezoelectric material becomes tetragonal. Forexample, the temperature for the polarization is preferably 60° C. to150° C., but the optimal conditions are somewhat different depending onthe composition of the piezoelectric material forming the element. Anelectric field to be applied to perform the polarization treatment ispreferably 8 kV/cm to 20 kV/cm. In addition, it is desirable to end theapplication of the electric field after decreasing an ambienttemperature to a temperature at which the piezoelectric material becomesorthorhombic, for obtaining an excellent piezoelectric constant.

(Measurements of Piezoelectric Constant and Mechanical Quality Factor)

To measure the piezoelectric constant and the mechanical quality factorof the piezoelectric element, first, the results of measuring theresonant frequency and the antiresonant frequency using a commercialimpedance analyzer (4194A, manufactured by Agilent Technologies, Inc.)are obtained. Then, using the measurement results, the piezoelectricconstant and the mechanical quality factor can be obtained throughcalculation based on Japan Electronics and Information TechnologyIndustries Association (JEITA) standard (EM-4501). Hereinafter, thismethod is referred to as a “resonance-antiresonance method”.

(Measurements of Phase Transition Temperature T_(to) and CurieTemperature T_(c))

The phase transition temperature T_(to) and the Curie temperature T_(c)can be obtained by measuring the capacitance of a sample using animpedance analyzer (4194A, manufactured by Agilent Technologies, Inc.)while changing the temperature of the sample. Simultaneously, thetemperature dependence of the dielectric loss tangent can also bemeasured and obtained using the impedance analyzer. The phase transitiontemperature T_(to) is a temperature at which the crystal system changesfrom tetragonal to orthorhombic. To measure the phase transitiontemperature T_(to), the temperature of the sample is once lowered fromroom temperature to −100° C. and then raised to 150° C., and thedielectric constant is measured while cooling the sample. Then, thetemperature at which a value obtained by differentiating the measureddielectric constant by the temperature of the sample is maximum ismeasured. The measured temperature is defined as the phase transitiontemperature T_(to).

On the other hand, the Curie temperature T_(c) is a temperature at whichthe dielectric constant is a local maximum near the phase transitiontemperature between a ferroelectric phase (a tetragonal phase) and aparaelectric phase (a cubic phase). The dielectric constant is measuredwhile heating the sample, and a temperature at which the value of themeasured dielectric constant is a local maximum is measured. Themeasured temperature is defined as the Curie temperature T_(c).

(Multilayered Piezoelectric Element)

Next, a multilayered piezoelectric element according to the presentinvention will be described.

The multilayered piezoelectric element according to the presentinvention is a multilayered piezoelectric element in which a pluralityof piezoelectric material layers and a plurality of electrode layersincluding an internal electrode are alternately stacked. A piezoelectricmaterial forming the piezoelectric material layers is formed of thepiezoelectric material according to the present invention.

FIGS. 2A and 2B are schematic cross-sectional views each illustratingthe configuration of the multilayered piezoelectric element according toan exemplary embodiment of the present invention. The multilayeredpiezoelectric element according to the present invention includespiezoelectric material layers 54 and electrode layers including aninternal electrode 55, and is a multilayered piezoelectric element inwhich the piezoelectric material layers 54 and the electrode layers arealternately stacked. The piezoelectric material layers 54 are eachformed of the above piezoelectric material. The electrode layers mayinclude external electrodes such as a first electrode 51 and a secondelectrode 53 in addition to the internal electrode 55.

FIG. 2A illustrates the configuration of the multilayered piezoelectricelement according to the present invention, in which two piezoelectricmaterial layers 54 and the single internal electrode 55 are alternatelystacked, and this multilayered structure is sandwiched between the firstelectrode 51 and the second electrode 53. As illustrated in FIG. 2B, thenumbers of piezoelectric material layers and internal electrodes may beincreased, and there is no limit on the number of layers. In themultilayered piezoelectric element in FIG. 2B, nine piezoelectricmaterial layers 504 and eight internal electrodes 505 (505 a or 505 b)are alternately stacked. This multilayered structure is formed bysandwiching the piezoelectric material layers 504 between a firstelectrode 501 and a second electrode 503, and includes an externalelectrode 506 a and an external electrode 506 b for short-circuiting thealternately formed internal electrodes.

The sizes and the shapes of the internal electrodes 55 and 505 and theexternal electrodes 506 a and 506 b may not necessarily need to be thesame as those of the piezoelectric material layers 54 and 504. Further,each of the internal electrodes 55 and 505 and the external electrodes506 a and 506 b may be divided into a plurality of parts.

Each of the internal electrodes 55 and 505, the external electrodes 506a and 506 b, the first electrodes 51 and 501, and the second electrodes53 and 503 is formed of a conductive layer having a thickness of about 5nm to 10 μm. The material of the electrode is not particularly limited,and may be a material normally used for a piezoelectric element.Examples of the material include metals such as Ti, Pt, Ta, Ir, Sr, In,Sn, Au, Al, Fe, Cr, Ni, Pd, Ag, and Cu, and compounds of these. Each ofthe internal electrodes 55 and 505 and the external electrodes 506 a and506 b may be formed of one of these or a mixture or an alloy of two ormore of these, or may be formed by stacking two or more of these.Further, the plurality of electrodes may be different in material fromeach other.

Each of the internal electrodes 55 and 505 contains Ag and Pd, and theweight ratio of M1/M2 is preferably 0.25≤M1/M2≤4.0, and more preferably2.3≤M1/M2≤4.0 where the weight of the contained Ag is M1 and the weightof the contained Pd is M2. If the weight ratio of M1/M2 is less than0.25, the sintering temperature of the internal electrode is high, whichis not desirable. If, on the other hand, the weight ratio of M1/M2 isgreater than 4.0, the internal electrode is formed in an insular manner,and therefore is not uniform in the surface, which is not desirable.

In terms of the low cost of the electrode material, it is desirable thateach of the internal electrodes 55 and 505 should contain at least oneof Ni and Cu. If at least one of Ni and Cu is used for each of theinternal electrodes 55 and 505, it is desirable to sinter themultilayered piezoelectric element according to the present invention ina reducing atmosphere.

As illustrated in FIG. 2B, the plurality of electrodes including theinternal electrodes 505 may be short-circuited to each other so that thedriving voltage is in phase. For example, the internal electrodes 505 aand the first electrode 501 may be short-circuited to each other by theexternal electrode 506 a. The internal electrodes 505 b and the secondelectrode 503 may be short-circuited to each other by the externalelectrode 506 b. The internal electrodes 505 a and the internalelectrodes 505 b may be alternately arranged. Further, the form ofshort-circuiting electrodes is not limited. An electrode or wiring forshort circuit may be provided on the side surface of the multilayeredpiezoelectric element. Alternatively, a through-hole may be providedthrough the piezoelectric material layers 504, and a conductive materialmay be provided inside the through-hole, thereby short-circuitingelectrodes to each other.

(Liquid Discharge Head)

Next, a liquid discharge head according to the present invention will bedescribed.

The liquid discharge head according to the present invention includes atleast a liquid chamber including a vibrating unit provided with thepiezoelectric element or the multilayered piezoelectric element, and adischarge port communicating with the liquid chamber.

FIGS. 3A and 3B are schematic diagrams illustrating the configuration ofthe liquid discharge head according to an exemplary embodiment of thepresent invention. As illustrated in FIGS. 3A and 3B, the liquiddischarge head according to the present invention is a liquid dischargehead including a piezoelectric element 101 according to the presentinvention. The piezoelectric element 101 is a piezoelectric elementincluding at least a first electrode 1011, a piezoelectric material1012, and a second electrode 1013. The piezoelectric material 1012 ispatterned where necessary, as illustrated in FIG. 3B.

FIG. 3B is a schematic diagram illustrating the liquid discharge head.The liquid discharge head includes a discharge port 105, an individualliquid chamber 102, a communication hole 106, which connects theindividual liquid chamber 102 and the discharge port 105, a liquidchamber partition wall 104, a common liquid chamber 107, a diaphragm103, and the piezoelectric element 101. In FIG. 3B, the piezoelectricelement 101 is rectangular. Alternatively, the shape of thepiezoelectric element 101 may be other than a rectangle, such as anellipse, a circle, or a parallelogram. Generally, the piezoelectricmaterial 1012 is shaped along the shape of the individual liquid chamber102.

FIG. 3A illustrates the details of the vicinity of the piezoelectricelement 101, which is included in the liquid discharge head according tothe present invention. FIG. 3A is a cross-sectional view, in the widthdirection, of the piezoelectric element 101 illustrated in FIG. 3B. Thecross-sectional shape of the piezoelectric element 101 is represented asa rectangle, but may be a trapezoid or an inverted trapezoid.

In FIG. 3A, the first electrode 1011 is used as a lower electrode, andthe second electrode 1013 is used as an upper electrode. However, thearrangement of the first electrode 1011 and the second electrode 1013 isnot limited to this. For example, the first electrode 1011 may be usedas a lower electrode, or may be used as an upper electrode. Similarly,the second electrode 1013 may be used as an upper electrode, or may beused as a lower electrode. Further, a buffer layer 108 may be presentbetween the diaphragm 103 and the lower electrode. The names of thesecomponents differ depending on the method for manufacturing the device,and the effects of the present invention can be obtained in any case.

In the liquid discharge head, the diaphragm 103 moves up and down by theexpansion and contraction of the piezoelectric material 1012, therebyapplying pressure to liquid in the individual liquid chamber 102. As aresult, the liquid is discharged from the discharge port 105. The liquiddischarge head according to the present invention can be used for aprinter or used for the manufacturing of an electronic device.

The thickness of the diaphragm 103 is 1.0 μm or more and 15 μm or less,and preferably 1.5 μm or more and 8 μm or less. The material of thediaphragm 103 is not limited, but is preferably Si. Boron or phosphorusmay be doped into the Si of the diaphragm 103. Further, the buffer layer108 or the electrode on the diaphragm 103 may constitute a part of thediaphragm 103. The thickness of the buffer layer 108 is 5 nm or more and300 nm or less, and preferably 10 nm or more and 200 nm or less. Thesize of the discharge port 105 is an equivalent circular diameter of 5μm or more and 40 μm or less. The shape of the discharge port 105 may bea circle, a star shape, a square, or a triangle.

(Liquid Discharge Apparatus)

Next, a liquid discharge apparatus according to the present inventionwill be described. The liquid discharge apparatus according to thepresent invention includes a stage for an object and the liquiddischarge head.

As an example of the liquid discharge apparatus according to the presentinvention, an inkjet recording apparatus illustrated in FIGS. 4 and 5 isgiven. FIG. 5 illustrates a state where components 885 and 887 areremoved from exteriors 882, 883, 884 of a liquid discharge apparatus (aninkjet recording apparatus) 881 illustrated in FIG. 4. The inkjetrecording apparatus 881 includes an automatic feeding unit 897, whichautomatically feeds a recording sheet as an object into an apparatusmain body 896. Further, the inkjet recording apparatus 881 includesthree units for guiding to a predetermined recording position therecording sheet fed from the automatic feeding unit 897, and guiding therecording sheet from the recording position to a discharge port 898.That is, the three units are a conveyance unit 899, which is a stage foran object, a recording unit 891, which performs recording onto therecording sheet conveyed to the recording position, and a recovery unit890, which performs a recovery process on the recording unit 891. Therecording unit 891 includes a carriage 892, which accommodates theliquid discharge head according to the present invention and istransported back and forth on a rail.

In such an inkjet recording apparatus, if the carriage 892 istransported on the rail according to an electric signal sent from acomputer and a driving voltage is applied to electrodes sandwiching apiezoelectric material, the piezoelectric material is displaced. Thedisplacement of the piezoelectric material applies a pressure onto theindividual liquid chamber 102 through the diaphragm 103 illustrated inFIG. 3B, and ink is discharged from the discharge ports 105, therebyperforming printing.

The liquid discharge apparatus according to the present invention canuniformly discharge liquid at high speed and can be downsized.

In the above example, a printer has been exemplified. Alternatively, theliquid discharge apparatus according to the present invention can beused for a printing apparatus such as an inkjet recording apparatus of afacsimile, a multifunction peripheral, or a copying machine, anindustrial liquid discharge apparatus, or a drawing apparatus fordrawing on a target object.

Additionally, a user can select a desired object according to use. Theconfiguration may be such that the liquid discharge head moves relativeto an object placed on the stage.

(Ultrasonic Motor)

Next, an ultrasonic motor according to the present invention will bedescribed. The ultrasonic motor according to the present inventionincludes at least a vibrating member provided with the piezoelectricelement or the multilayered piezoelectric element, and a moving memberin contact with the vibrating member.

FIGS. 6A and 6B are schematic diagrams illustrating the configuration ofthe ultrasonic motor according to the present invention. FIG. 6Aillustrates an ultrasonic motor including the piezoelectric elementaccording to the present invention that is composed of a single plate.The ultrasonic motor includes an oscillator 201, a rotor 202, which isin contact with a sliding surface of the oscillator 201 by the pressingforce of a pressing spring (not illustrated), and an output shaft 203,which is integrally formed with the rotor 202. The oscillator 201includes a metallic elastic ring 2011, a piezoelectric element 2012according to the present invention, and an organic adhesive 2013 (anepoxy adhesive or a cyanoacrylate adhesive), which adheres thepiezoelectric element 2012 to the elastic ring 2011. The piezoelectricelement 2012 according to the present invention includes a piezoelectricmaterial sandwiched between a first electrode (not illustrated) and asecond electrode (not illustrated).

If two alternating voltages having phases different by an odd multipleof π/2 are applied to the piezoelectric element 2012 according to thepresent invention, a flexural traveling wave occurs in the oscillator201, and each point on the sliding surface of the oscillator 201 makesan elliptical motion. If the rotor 202 is in pressure contact with thesliding surface of the oscillator 201, the rotor 202 is subjected to thefrictional force of the oscillator 201 and rotates in a directionopposite to that of the flexural traveling wave. A driven member (notillustrated) is joined with the output shaft 203 and driven by therotational force of the rotor 202. If a voltage is applied to thepiezoelectric material, the piezoelectric material expands and contractsby the transverse piezoelectric effect. If an elastic member made of ametal is joined with the piezoelectric element 2012, the elastic memberis bent by the expansion and contraction of the piezoelectric material.The type of ultrasonic motor described here uses this principle.

Next, FIG. 6B exemplifies an ultrasonic motor including a piezoelectricelement having a multilayered structure. An oscillator 204 includes amultilayered piezoelectric element 2042, which is sandwiched betweencylindrical metallic elastic members 2041. The multilayeredpiezoelectric element 2042 is an element including a plurality ofstacked piezoelectric materials (not illustrated), and includes a firstelectrode and a second electrode on the outer surfaces of the stackedlayers and internal electrodes between the inner surfaces of the stackedlayers. The metallic elastic members 2041 are fastened to each otherwith bolts to fix the piezoelectric element 2042 in a sandwich manner,thereby forming the oscillator 204.

Alternating voltages having different phases are applied to themultilayered piezoelectric element 2042, thereby causing the oscillator204 to excite two oscillations orthogonal to each other. These twooscillations are combined together to form a circular oscillation fordriving a leading edge portion of the oscillator 204. In an upperportion of the oscillator 204, an annular groove is formed in aconstricted manner to increase the displacement of the oscillation forthe driving. A rotor 205 is in pressure contact with the oscillator 204by a pressurizing spring 206, thereby obtaining a frictional force forthe driving. The rotor 205 is rotatably supported by a bearing.

(Optical Device)

Next, an optical device according to the present invention will bedescribed. The optical device according to the present inventionincludes a driving unit provided with ultrasonic motor.

FIGS. 7A and 7B are main cross-sectional views of an interchangeablelens barrel of a single-lens reflex camera, which is an example of theoptical device according to a suitable exemplary embodiment of thepresent invention. Further, FIG. 8 is an exploded perspective view ofthe interchangeable lens barrel of the single-lens reflex camera, whichis an example of the optical device according to a suitable exemplaryembodiment of the present invention. To a mount 711, which is detachablyattached to the camera, a fixed barrel 712, an advancement guide barrel713, and a front lens group barrel 714 for supporting a front lens group701 are fixed. These components are fixed members of the interchangeablelens barrel.

In the advancement guide barrel 713, an advancement guide groove 713 ais formed for guiding a focus lens 702 in the optical axis direction. Toa rear lens group barrel 716, which holds the focus lens 702, camrollers 717 a and 717 b, which protrude outward in the radial direction,are fixed with a shaft screw 718. The cam roller 717 a fits into theadvancement guide groove 713 a.

A cam ring 715 turnably fits into the inner circumference of theadvancement guide barrel 713. A roller 719, which is fixed to the camring 715, fits into an annular groove 713 b of the advancement guidebarrel 713, thereby regulating the relative movements of the advancementguide barrel 713 and the cam ring 715 in the optical axis direction. Inthe cam ring 715, a cam groove 715 a is formed for the focus lens 702,and the cam roller 717 b also fits into the cam groove 715 a.

On the outer circumferential side of the fixed barrel 712, a rotationtransmission ring 720 is placed. The rotation transmission ring 720 isrotatably held at a fixed position relative to the fixed barrel 712 by aball race 727. In the rotation transmission ring 720, a driven roller722 is rotatably held on a shaft 720 f, which extends radially from therotation transmission ring 720. A larger-diameter portion 722 a of thedriven roller 722 is in contact with a mount-side end surface 724 b of amanual focus ring 724. Further, a smaller-diameter portion 722 b of thedriven roller 722 is in contact with a joint member 729. Actually, sixdriven rollers 722 are placed at regular intervals on the outercircumference of the rotation transmission ring 720 and are each formedbased on the above relationship.

In an inner circumferential portion of the manual focus ring 724, a lowfriction sheet (washer member) 733 is placed and sandwiched between amount-side end surface 712 a of the fixed barrel 712 and a front-sideend surface 724 a of the manual focus ring 724. Further, the outercircumferential surface of the low friction sheet 733 is ring-shaped andcircumferentially fits with an inner circumference 724 c of the manualfocus ring 724. Further, the inner circumference 724 c of the manualfocus ring 724 circumferentially fits with an outer circumferentialportion 712 b of the fixed barrel 712. The low friction sheet 733functions to reduce friction in a rotation ring mechanism having theconfiguration in which the manual focus ring 724 rotates about theoptical axis relative to the fixed barrel 712.

The larger-diameter portion 722 a of the driven roller 722 and themount-side end surface 724 b of the manual focus ring 724 are in contactwith each other in a state where a pressing force is applied to thelarger-diameter portion 722 a and the mount-side end surface 724 b bythe force of a wave washer 726 pressing an ultrasonic motor 725 in theforward direction of the lens 702. Further, similarly, thesmaller-diameter portion 722 b of the driven roller 722 and the jointmember 729 are also in contact with each other in a state where amoderate pressing force is applied to the smaller-diameter portion 722 band the joint member 729 by the force of the wave washer 726 pressingthe ultrasonic motor 725 in the forward direction of the lens 702. Themovement of the wave washer 726 in the direction of the mount 711 isregulated by a washer 732, which is bayonet-coupled to the fixed barrel712. The spring force (urging force) generated by the wave washer 726 istransmitted to the ultrasonic motor 725 and further to the driven roller722 and also results in the force of the manual focus ring 724 pressingthe mount-side end surface 712 a of the fixed barrel 712. That is, themanual focus ring 724 is incorporated while being pressed against themount-side end surface 712 a of the fixed barrel 712 through the lowfriction sheet 733.

Thus, if the ultrasonic motor 725 is driven to rotate relative to thefixed barrel 712 by a control unit (not illustrated), the driven roller722 rotates about the shaft 720 f because the joint member 729 is infriction contact with the smaller-diameter portion 722 b of the drivenroller 722. If the driven roller 722 rotates about the shaft 720 f, as aresult, the rotation transmission ring 720 rotates about the opticalaxis (an autofocus operation).

Further, if a rotational force about the optical axis is applied to themanual focus ring 724 by a manual operation input unit (notillustrated), the manual focus ring 724 acts as follows. That is, sincethe mount-side end surface 724 b of the manual focus ring 724 is inpressure contact with the larger-diameter portion 722 a of the drivenroller 722, the driven roller 722 rotates about the shaft 720 f due tothe frictional force. If the larger-diameter portion 722 a of the drivenroller 722 rotates about the shaft 720 f, the rotation transmission ring720 rotates about the optical axis. At this time, the friction holdingpower of a rotor 725 c and a stator 725 b prevents the ultrasonic motor725 from rotating (a manual focus operation).

To the rotation transmission ring 720, two focus keys 728 are attachedat positions opposed to each other, and each fit with a notch portion715 b, which is provided at the leading edge of the cam ring 715. Thus,if an autofocus operation or a manual focus operation is performed torotate the rotation transmission ring 720 about the optical axis, therotational force of the rotation transmission ring 720 is transmitted tothe cam ring 715 through the focus keys 728. If the cam ring 715 isrotated about the optical axis, the rear lens group barrel 716, of whichthe rotation is regulated by the cam roller 717 a and the advancementguide groove 713 a, advances or retreats along the cam groove 715 a ofthe cam ring 715 by the cam roller 717 b. Consequently, the focus lens702 is driven, and a focus operation is performed.

While an interchangeable lens barrel of a single-lens reflex camera hasbeen described as an example of the optical device according to thepresent invention, the present invention is applicable to an opticaldevice including a driving unit provided with an ultrasonic motor, suchas a compact camera, an electronic still camera, or a camera-equippedpersonal digital assistant, regardless of the type of camera.

(Oscillatory Device and Dust Removing Device)

An oscillatory device for conveying or removing a particle, a powder, ora droplet is widely used for an electronic device.

As an example of an oscillatory device according to the presentinvention, a dust removing device using the piezoelectric elementaccording to the present invention will be described below. Theoscillatory device according to the present invention includes avibrating member including a diaphragm provided with the abovepiezoelectric element or the above multilayered piezoelectric element.The dust removing device according to the present invention includes avibrating unit provided with the oscillatory device.

FIGS. 9A and 9B are schematic diagrams illustrating a dust removingdevice according to an exemplary embodiment of the present invention. Adust removing device 310 includes a plate-shaped piezoelectric element330 and a diaphragm 320. The piezoelectric element 330 may be themultilayered piezoelectric element according to the present invention.The material of the diaphragm 320 is not limited. When, however, thedust removing device 310 is used for an optical device, a translucentmaterial or a light-reflective material can be used for the diaphragm320.

FIGS. 10A to 10C are schematic diagrams illustrating the configurationof the piezoelectric element 330 in FIGS. 9A and 9B. FIGS. 10A and 10Cillustrate the configurations of the front and back surfaces of thepiezoelectric element 330. FIG. 10B illustrates the configuration of theside surface of the piezoelectric element 330. As illustrated in FIGS.9A and 9B, the piezoelectric element 330 includes a piezoelectricmaterial 331, a first electrode 332, and a second electrode 333. Thefirst electrode 332 and the second electrode 333 are placed to beopposed to each other on the plate surfaces of the piezoelectricmaterial 331. Similarly to FIGS. 9A and 9B, the piezoelectric element330 may be the multilayered piezoelectric element according to thepresent invention. In this case, the piezoelectric material 331 has analternate structure including piezoelectric material layers and internalelectrodes, and the internal electrodes are alternately short-circuitedto the first electrode 332 or the second electrode 333. Thus, it ispossible to provide driving waveforms different in phase to thepiezoelectric material layers. In FIG. 10C, the surface of thepiezoelectric element 330 which appears on the front side and on whichthe first electrode 332 is provided is defined as a first electrodesurface 336. In FIG. 10A, the surface of the piezoelectric element 330which appears on the front side and on which the second electrode 333 isprovided is defined as a second electrode surface 337.

In the present invention, an “electrode surface” refers to the surfaceof a piezoelectric element on which an electrode is provided. Forexample, as illustrated in FIG. 10B, the first electrode 332 may extendaround the piezoelectric material 331 to the second electrode surface337.

As illustrated in FIGS. 9A and 9B, the piezoelectric element 330 and thediaphragm 320 are fixedly attached to the plate surface of the diaphragm320 on the first electrode surface 336 of the piezoelectric element 330.Then, the driving of the piezoelectric element 330 causes a stressbetween the piezoelectric element 330 and the diaphragm 320, therebycausing the diaphragm 320 to generate an out-of-plane oscillation. Thedust removing device 310 according to the present invention is anapparatus for removing, by the out-of-plane oscillation of the diaphragm320, foreign matter such as dust attached to the surface of thediaphragm 320. The “out-of-plane oscillation” means an elasticoscillation that displaces the diaphragm 320 in the optical axisdirection, that is, the thickness direction of the diaphragm 320.

FIGS. 11A and 11B are schematic diagrams illustrating the oscillationprinciple of the dust removing device 310 according to the presentinvention. FIG. 11A represents a state where in-phase alternatingvoltages are applied to a pair of left and right piezoelectric elements330 to cause the diaphragm 320 to generate an out-of-plane oscillation.The polarization direction of the piezoelectric material forming thepair of left and right piezoelectric elements 330 is the same as thethickness direction of each piezoelectric element 330. The dust removingdevice 310 is driven in the seventh oscillation mode. FIG. 11Brepresents a state where antiphase alternating voltages, which differ inphase by 180°, are respectively applied to the pair of left and rightpiezoelectric elements 330 to cause the diaphragm 320 to generate anout-of-plane oscillation. The dust removing device 310 is driven in thesixth oscillation mode. The dust removing device 310 according to thepresent invention is an apparatus capable of effectively removing dustattached to the surface of a diaphragm, by appropriately using either ofat least two oscillation modes.

(Imaging Apparatus)

Next, an imaging apparatus according to the present invention will bedescribed. The imaging apparatus according to the present invention isan imaging apparatus including at least the dust removing device and animage sensor unit. The diaphragm of the dust removing device is providedon the light-receiving surface side of the image sensor unit. FIGS. 12and 13 are diagrams illustrating a digital single-lens reflex camera,which is an example of the imaging apparatus according to a suitableexemplary embodiment of the present invention.

FIG. 12 is a front perspective view of a camera main body 601 as viewedfrom an object side, and illustrates a state where an imaging lens unitis removed. FIG. 13 is an exploded perspective view of the generalconfiguration of the inside of the camera for illustrating theperipheral structure of the dust removing device according to thepresent invention and an imaging unit 400.

In the camera main body 601, a mirror box 605 is provided, to which animaging light flux having passed through an imaging lens is guided. Inthe mirror box 605, a main mirror (quick-return mirror) 606 is disposed.The main mirror 606 can enter a state of being held at an angle of 45°with respect to an imaging optical axis to guide the imaging light fluxin the direction of a pentagonal roof mirror (not illustrated), or astate of being held at a position where the main mirror 606 is retractedfrom the imaging light flux to guide the imaging light flux in thedirection of an image sensor (not illustrated).

On the object side of a main body chassis 300, which is the framework ofthe camera main body 601, the mirror box 605 and a shutter unit 200 aredisposed in this order from the object side. Further, on thephotographer side of the main body chassis 300, the imaging unit 400 isdisposed. The imaging unit 400 is provided by being adjusted so that theimaging surface of the image sensor is placed at a predetermineddistance from and parallel to the attachment surface of a mount unit602, which serves as a reference for the attachment of the imaging lensunit.

The imaging unit 400 includes a vibrating member of the dust removingdevice and an image sensor unit. Further, the vibrating member of thedust removing device and the light-receiving surface of the image sensorunit are provided coaxially in order.

While a digital single-lens reflex camera has been described as anexample of the imaging apparatus according to the present invention, aninterchangeable imaging lens unit camera, such as a mirrorless digitalsingle-lens camera, which does not include the mirror box 605, may beused. Further, the present invention is also applicable to particularlya device that requires the removal of dust attached to the surface of anoptical component, among various imaging apparatuses or electronic andelectrical devices including an imaging apparatus, such as aninterchangeable imaging lens unit video camera, a copying machine, afacsimile, and a scanner.

(Electronic Device)

Next, an electronic device according to the present invention will bedescribed. The electronic device according to the present inventionincludes a piezoelectric acoustic component provided with thepiezoelectric element or the multilayered piezoelectric element.Examples of the piezoelectric acoustic component include a loudspeaker,a buzzer, a microphone, and a surface acoustic wave (SAW) device.

FIG. 14 is an overall perspective view of a digital camera, which is anexample of the electronic device according to a suitable exemplaryembodiment of the present invention, as viewed from the front of a mainbody 931 of the digital camera. On the front surface of the main body931, an optical apparatus 901, a microphone 914, a flash light-emittingunit 909, and an auxiliary light unit 916 are placed. The microphone 914is built into the main body 931, and therefore is indicated by a dashedline. In front of the microphone 914, a hole shape for picking up asound from outside is provided.

On the upper surface of the main body 931, a power button 933, aloudspeaker 912, a zoom lever 932, and a shutter release button 908 forperforming a focusing operation are placed. The loudspeaker 912 is builtinto the main body 931, and therefore is indicated by a dashed line. Infront of the loudspeaker 912, a hole shape for transmitting a sound tothe outside is provided.

The piezoelectric acoustic component according to the present inventionis used for at least one of the microphone 914, the loudspeaker 912, anda surface acoustic wave device.

While a digital camera has been described as an example of theelectronic device according to the present invention, the electronicdevice according to the present invention is also applicable to variouselectronic devices including a piezoelectric acoustic component, such asa sound reproduction device, a sound recording device, a mobile phone,and an information terminal.

As described above, the piezoelectric element and the multilayeredpiezoelectric element according to the present invention are suitablyused for a liquid discharge head, a liquid discharge apparatus, anultrasonic motor, an optical device, an oscillatory device, a dustremoving device, an imaging apparatus, and an electronic device. Thepiezoelectric element and the multilayered piezoelectric elementaccording to the present invention are suitably used particularly fordriving at low temperature.

By using the piezoelectric element and the multilayered piezoelectricelement according to the present invention, it is possible to provide aliquid discharge head having a nozzle density and a discharge velocitythat are equivalent to or greater than that of when a piezoelectricelement containing lead is used.

By using the liquid discharge head according to the present invention,it is possible to provide a liquid discharge apparatus having adischarge velocity and discharge accuracy that are equivalent to orgreater than that of when a piezoelectric element containing lead isused.

By using the piezoelectric element and the multilayered piezoelectricelement according to the present invention, it is possible to provide anultrasonic motor having a driving force and durability that areequivalent to or greater than that of when a piezoelectric elementcontaining lead is used.

By using the ultrasonic motor according to the present invention, it ispossible to provide an optical device having durability and operationaccuracy that are equivalent to or greater than that of when apiezoelectric element containing lead is used.

By using the piezoelectric element and the multilayered piezoelectricelement according to the present invention, it is possible to provide anoscillatory device having vibration performance and durability that areequivalent to or greater than that of when a piezoelectric elementcontaining lead is used.

By using the oscillatory device according to the present invention, itis possible to provide a dust removing device having dust removingefficiency and durability that are equivalent to or greater than that ofwhen a piezoelectric element containing lead is used.

By using the dust removing device according to the present invention, itis possible to provide an imaging apparatus having a dust removingfunction that is equivalent to or better than that of when apiezoelectric element containing lead is used.

By using a piezoelectric acoustic component including the piezoelectricelement or the multilayered piezoelectric element according to thepresent invention, it is possible to provide an electronic device havingsound production properties that are equivalent to or better that ofwhen a piezoelectric element containing lead is used.

The piezoelectric material according to the present invention can beused for devices such as an ultrasonic oscillator, a piezoelectricactuator, a piezoelectric sensor, and a ferroelectric memory, inaddition to a liquid discharge head and a motor.

EXAMPLES

The present invention will be described more specifically below withexamples. The present invention, however, is not limited to thefollowing examples.

The piezoelectric material according to the present invention wasproduced by the following procedure.

(Piezoelectric Material)

(Piezoelectric Material of Example 1)

Raw materials corresponding to a compositionBa_(1.0005)(Ti_(0.960)Zr_(0.040))O₃, which is represented by the generalformula (1) of Ba_(a)(Ti_(1-x)Zr_(x))O₃, where x=0.040 and a=1.0005,were weighed in the following manner.

Raw material powders of barium titanate having an average particlediameter of 100 nm and a purity of 99.99% or more and barium zirconatehaving an average particle diameter of 300 nm and a purity of 99.99% ormore were prepared by a solid phase method. On that basis, the rawmaterial powders were weighed so that the proportions of Ba, Ti, and Zrresulted in the composition Ba_(1.0005)(Ti_(0.960)Zr_(0.040))O₃.Further, barium carbonate and titanium oxide were used to adjust “a”indicating the ratio of the molar amount of Ba at the A site to themolar amount of Ti and Zr at the B site.

Manganese dioxide was weighed so that the amount of an Mn elementcontained as the first auxiliary component was 0.015 moles relative to 1mole of the composition Ba_(1.0005)(Ti_(0.960)Zr_(0.040))O₃. Bismuthoxide was weighed so that the amount of a Bi element contained as thesecond auxiliary component was 0.00200 moles relative to 1 mole of themetal oxide as the main component. Silicon dioxide was weighed so that,as one of the third auxiliary components, Si was 0.0670 parts by weightin terms of metal relative to 100 parts by weight of the metal oxide asthe main component. Boron oxide was weighed so that, as one of the thirdauxiliary components, B was 0.0330 parts by weight in terms of metalrelative to 100 parts by weight of the metal oxide as the maincomponent.

These weighed powders were mixed together by dry blending for 24 hours,using a ball mill. Then, 3 parts by weight of a PVA binder was attachedto the surface of the mixed powder using a spray dryer apparatus,thereby granulating the mixed powder.

Next, a metal mold was filled with the obtained granulated powder, and amolding pressure of 200 MPa was applied to the granulated powder using apress molding machine, thereby preparing a disk-shaped compact. Thecompact was further pressed using a cold isostatic pressing machine, butthe obtained results were similar.

The obtained compact was placed in an electric furnace, held for 4 hoursunder the condition of a maximum sintering temperature T_(max) of 1200°C., and sintered in the atmosphere for a total of 24 hours, therebyobtaining a ceramic including the piezoelectric material according tothe present invention.

Then, the average equivalent circular diameter and the relative densityof the crystal grains forming the obtained ceramic were evaluated. As aresult, the average equivalent circular diameter was 3.2 μm, and therelative density was 98.9%. The crystal grains were observed mainlyusing a polarizing microscope. To specify the grain diameter of a smallcrystal grain, an SEM was used. Photographic images obtained byphotographing the crystal grains using the polarizing microscope and theSEM were subjected to image processing, and the average equivalentcircular diameter was calculated. Further, the relative density wasevaluated using the Archimedes' principle.

Next, the obtained ceramic was polished so as to have a thickness of 0.5mm, and the crystal structure of the ceramic was analyzed by X-raydiffraction. As a result, only peaks corresponding to a perovskitestructure were observed.

Further, the composition of the obtained ceramic was evaluated by an ICPemission spectroscopic analysis. As a result, it was understood that thepiezoelectric material included as the main component a metal oxide thatcan be represented by a chemical formulaBa_(1.0005)(Ti_(0.960)Zr_(0.040))O₃. Further, it was also understoodthat the Mn element was 0.015 moles and the Bi element was 0.00200moles, relative to 1 mole of the metal oxide as the main component.Further, it was also understood that 0.0670 parts by weight of Si interms of metal and 0.0330 parts by weight of B in terms of metal werecontained relative to 100 parts by weight of the metal oxide as the maincomponent. As a result, it was understood that the weighed compositioncoincided with the composition after sintering.

Further, the crystal grains were observed again, but the averageequivalent circular diameter was not significantly different betweenbefore and after the polishing.

(Piezoelectric Materials of Examples 2 to 29)

Piezoelectric materials of Examples 2 to 29 were prepared by processessimilar to those of Example 1. First, each raw material powder wasweighed so that the proportions of Ba, Ti, and Zr were as illustrated inTable 1. Barium carbonate and titanium oxide were used to adjust “a”indicating the ratio of the molar amount of Ba at the A site to themolar amount of Ti and Zr at the B site. Next, the sum (the combinedvalue) of the weighed barium titanate, barium zirconate, bariumcarbonate, and titanium oxide was converted into the chemical formulaBa_(a)(Ti_(1-x)Zr_(x))O₃. Manganese dioxide and bismuth oxide wereweighed so that the proportions of an Mn element as the first auxiliarycomponent and a Bi element as the second auxiliary component were asillustrated in Table 1 relative to 1 mole of the compound represented bythe chemical formula after the conversion. Further, silicon dioxide andboron oxide were weighed so that the proportions of the amounts ofcontained Si and B as the third auxiliary components were as illustratedin Table 1 in terms of metal relative to 100 parts by weight of thecompound represented by the chemical formula Ba_(a)(Ti_(1-x)Zr_(x))O₃after the conversion.

These weighed powders were mixed together by dry blending for 24 hours,using a ball mill. Then, 3 parts by weight of a PVA binder was attachedto the surface of the mixed powder using a spray dryer apparatus,thereby granulating the mixed powder.

Next, a metal mold was filled with the obtained granulated powder, and amolding pressure of 200 MPa was applied to the granulated powder using apress molding machine, thereby preparing a disk-shaped compact.

The obtained compact was placed in an electric furnace, held for 4 hoursunder the condition of a maximum sintering temperature T_(max) asillustrated in Table 1, and sintered in the atmosphere for a total of 24hours, thereby obtaining a ceramic formed of the piezoelectric materialaccording to the present invention.

Similarly to Example 1, the average equivalent circular diameter and therelative density were evaluated. The results are illustrated in Table 2.

Further, similarly to Example 1, the composition was analyzed. In allthe piezoelectric materials, the weighed composition of Ba, Ti, Zr, Mn,Bi, Si, and B coincided with the composition after sintering.

(Metal Oxide Materials of Comparative Examples 1 to 12)

Metal oxide materials for comparison were prepared by processes similarto those of Example 1, according to the proportions of the maincomponent, the first auxiliary component, the second auxiliarycomponent, and the third auxiliary components, the molar ratio a of theA site to the B site, and the condition of the maximum sinteringtemperature T_(max), as illustrated in Table 1.

Similarly to Example 1, the average equivalent circular diameter and therelative density were evaluated. The results are illustrated in Table 2.

Further, similarly to Example 1, the composition was analyzed. In allthe metal oxide materials, the weighed composition of Ba, Ti, Zr, Mn,Bi, Si, and B coincided with the composition after sintering.

TABLE 1 First Second Maximum Auxiliary Auxiliary Third AuxiliaryComponent Sintering Main Component Component Component Si B TotalTemperature Zr Ti A/B Mn Bi Parts by Parts by Parts by T_(max) x 1 − x amol mol Weight Weight Weight ° C. Example 1 0.040 0.960 1.0005 0.0150.00200 0.0670 0.0330 0.1000 1200 Example 2 0.060 0.940 0.9985 0.0100.00100 0.0670 0.0330 0.1000 1250 Example 3 0.060 0.940 1.0005 0.0100.00100 0.0670 0.0330 0.1000 1250 Example 4 0.050 0.950 0.9985 0.0100.00200 0.0670 0.0330 0.1000 1250 Example 5 0.040 0.960 0.9985 0.0100.00200 0.0670 0.0330 0.1000 1200 Example 6 0.020 0.980 0.9985 0.0100.00200 0.0670 0.0330 0.1000 1200 Example 7 0.130 0.870 0.9985 0.0050.00200 0.0670 0.0330 0.1000 1250 Example 8 0.100 0.900 0.9985 0.0050.00200 0.0670 0.0330 0.1000 1250 Example 9 0.040 0.960 0.9860 0.0050.00200 0.0670 0.0330 0.1000 1200 Example 10 0.040 0.960 1.0200 0.0050.00200 0.0670 0.0330 0.1000 1200 Example 11 0.040 0.960 0.9985 0.0050.00200 0.0010 0.0000 0.0010 1250 Example 12 0.040 0.960 0.9985 0.0050.00200 3.6700 1.3300 4.0000 1200 Example 13 0.040 0.960 0.9985 0.0050.00200 0.0005 0.0000 0.0005 1350 Example 14 0.040 0.960 0.9985 0.0050.00200 0.0000 0.0000 0.0000 1400 Example 15 0.040 0.960 0.9985 0.0050.00200 4.3300 1.6700 5.0000 1300 Example 16 0.040 0.960 0.9955 0.0020.00042 0.0670 0.0330 0.1000 1200 Example 17 0.040 0.960 0.9860 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 18 0.040 0.960 0.9900 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 19 0.040 0.960 0.9920 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 20 0.040 0.960 0.9955 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 21 0.040 0.960 0.9965 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 22 0.040 0.960 0.9975 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 23 0.040 0.960 0.9985 0.0020.00200 0.0670 0.0330 0.1000 1200 Example 24 0.040 0.960 0.9995 0.0020.00200 0.0670 0.0330 0.1000 1250 Example 25 0.040 0.960 1.0005 0.0020.00200 0.0670 0.0330 0.1000 1250 Example 26 0.040 0.960 1.0015 0.0020.00200 0.0670 0.0330 0.1000 1250 Example 27 0.040 0.960 1.0100 0.0020.00200 0.0670 0.0330 0.1000 1250 Example 28 0.040 0.960 1.0200 0.0020.00200 0.0670 0.0330 0.1000 1250 Example 29 0.040 0.960 0.9955 0.0020.00850 0.0670 0.0330 0.1000 1200 Comparative 0.140 0.860 0.9985 0.0050.00100 0.0670 0.0330 0.1000 1250 Example 1 Comparative 0.060 0.9400.9985 0.010 0.00000 0.0670 0.0330 0.1000 1250 Example 2 Comparative0.050 0.950 0.9985 0.010 0.00000 0.0670 0.0330 0.1000 1250 Example 3Comparative 0.040 0.960 0.9840 0.005 0.00200 0.0670 0.0330 0.1000 1200Example 4 Comparative 0.040 0.960 1.0210 0.005 0.00200 0.0670 0.03300.1000 1200 Example 5 Comparative 0.040 0.960 0.9955 0.001 0.002000.0670 0.0330 0.1000 1200 Example 6 Comparative 0.040 0.960 0.9985 0.0180.00200 0.0670 0.0330 0.1000 1200 Example 7 Comparative 0.040 0.9600.9955 0.005 0.00040 0.0670 0.0330 0.1000 1200 Example 8 Comparative0.040 0.960 0.9955 0.005 0.00900 0.0670 0.0330 0.1000 1200 Example 9Comparative 0.030 0.970 0.9985 0.010 0.00000 0.0670 0.0330 0.1000 1200Example 10 Comparative 0.020 0.980 0.9985 0.010 0.00000 0.0670 0.03300.1000 1200 Example 11 Comparative 0.015 0.9985 0.9985 0.010 0.002000.0670 0.0330 0.1000 1200 Example 12

TABLE 2 Equivalent Circular Relative Diameter Density μm % Example 1 3.298.9 Example 2 3.1 98.5 Example 3 1.2 98.3 Example 4 2.8 98.7 Example 53.4 99.0 Example 6 4.1 98.9 Example 7 1.0 93.4 Example 8 1.0 93.6Example 9 8.0 99.1 Example 10 0.5 94.2 Example 11 3.9 99.1 Example 123.9 95.3 Example 13 3.9 98.7 Example 14 4.1 99.5 Example 15 4.1 98.6Example 16 3.3 97.7 Example 17 7.6 98.7 Example 18 7.2 99.1 Example 195.6 98.9 Example 20 3.1 99.3 Example 21 2.4 98.7 Example 22 2.1 98.6Example 23 1.7 98.2 Example 24 1.8 97.9 Example 25 1.2 97.6 Example 261.1 97.2 Example 27 0.7 94.0 Example 28 0.7 93.8 Example 29 2.8 99.0Comparative 0.4 91.2 Example 1 Comparative 3.5 97.9 Example 2Comparative 3.5 99.1 Example 3 Comparative 15.1 97.5 Example 4Comparative 0.3 92.2 Example 5 Comparative 3.1 98.9 Example 6Comparative 2.4 98.3 Example 7 Comparative 2.3 96.5 Example 8Comparative 2.1 96.1 Example 9 Comparative 2.4 99.0 Example 10Comparative 2.9 98.3 Example 11 Comparative 3.7 98.4 Example 12(Production of Piezoelectric Element)

Next, the piezoelectric element according to the present invention wasproduced.

(Piezoelectric Elements of Examples 1 to 29)

Piezoelectric elements were produced using the piezoelectric materialsof Examples 1 to 29.

Gold electrodes, each having a thickness of 400 nm, were formed on bothfront and back surfaces of the disk-shaped ceramic by direct-current(DC) sputtering. Between each electrode and the ceramic, a titanium filmhaving a thickness of 30 nm was formed as an adhesion layer. The ceramicwith the electrodes was cut to produce a rectangular piezoelectricelement having a size of 10 mm×2.5 mm×0.5 mm.

The piezoelectric element was placed on a hot plate, the piezoelectricelement was heated so that the temperature of the piezoelectric elementsurface would be 100° C., and an electric field of 14 kV/cm was appliedto the heated piezoelectric element for 30 minutes. After thepiezoelectric element was cooled to 25° C. while retaining the electricfield, the application of the electric field was ended. Through such aprocedure, a polarization treatment was performed on the piezoelectricelement.

(Piezoelectric Elements of Comparative Examples 1 to 12)

Next, elements for comparison were produced and subjected to apolarization treatment by a method similar to those of Examples 1 to 29,using the metal oxide materials for comparison of Comparative Examples 1to 12.

(Evaluations of Properties of Piezoelectric Element)

Regarding the piezoelectric elements produced using the piezoelectricmaterials of Examples 1 to 29 and the elements for comparison producedusing the metal oxide materials of Comparative Examples 1 to 12, apiezoelectric constant d₃₁ and a mechanical quality factor Qm, at a roomtemperature of 25° C., of each piezoelectric element subjected to thepolarization treatment were evaluated. Further, the temperaturedependence of the dielectric loss tangent was measured using animpedance analyzer. The results are illustrated in table 3. In table 3,“−” in Comparative Example 5 indicates that a significant result was notobtained regarding the evaluation item because the resistivity of theelement was low and the element was not able to be sufficientlysubjected to the polarization treatment.

The piezoelectric constant d₃₁ and the mechanical quality factor Qm wereobtained by the resonance-antiresonance method. If the piezoelectricconstant d₃₁ is small, a large electric field is required to drive thedevice. Thus, such a piezoelectric constant is not suitable for drivingthe device. The piezoelectric constant d₃₁ is preferably 100 pm/V ormore, and more preferably 140 pm/V or more.

(Evaluations of Phase Transition Temperature T_(to) and CurieTemperature T_(c) of Piezoelectric Element)

Next, regarding the piezoelectric elements of Examples 1 to 29 and theelements for comparison of Comparative Examples 1 to 12, the phasetransition temperature T_(to) and the Curie temperature T_(c) wereevaluated. The phase transition temperature T_(to) and the Curietemperature T_(c) were calculated by measuring the capacitance of asample using an impedance analyzer (4194A, manufactured by AgilentTechnologies, Inc.) while changing the temperature of the sample. Thephase transition temperature T_(to) is a temperature at which, when thetemperature of the sample was once lowered from room temperature to−100° C. and then raised to 150° C., the crystal system changed fromtetragonal to orthorhombic. The phase transition temperature T_(to) wasdefined as a temperature at which, when the dielectric constant wasmeasured while cooling the sample, the value obtained by differentiatingthe measured dielectric constant by the sample temperature was maximum.The Curie temperature T_(c) is a temperature at which the dielectricconstant was a local maximum near the phase transition temperaturebetween a ferroelectric phase (a tetragonal phase) and a paraelectricphase (a cubic phase). The Curie temperature T_(c) was defined as atemperature at which, when the dielectric constant was measured whileheating the sample, the value of the measured dielectric constant was alocal maximum. The results are illustrated in table 3.

TABLE 3 Dielectric Loss T_(to) T_(c) d₃₁ Qm Tangent ° C. ° C. pm/V — —Example 1 26 114 124 1265 0.0056 Example 2 56 106 105 1237 0.0051Example 3 56 100 95 1336 0.0048 Example 4 34 108 119 978 0.0050 Example5 24 114 128 876 0.0057 Example 6 10 126 111 1137 0.0041 Example 7 70 7886 439 0.0038 Example 8 56 86 114 554 0.0046 Example 9 24 114 120 5940.0053 Example 10 18 114 112 243 0.0028 Example 11 24 114 139 757 0.0034Example 12 24 114 124 683 0.0034 Example 13 24 114 148 698 0.0036Example 14 24 114 152 722 0.0038 Example 15 24 114 142 589 0.0054Example 16 50 114 106 387 0.0040 Example 17 24 114 132 489 0.0053Example 18 24 114 147 473 0.0051 Example 19 24 114 149 523 0.0049Example 20 24 114 156 583 0.0044 Example 21 24 114 152 481 0.0045Example 22 22 114 148 342 0.0030 Example 23 20 114 129 289 0.0031Example 24 20 114 128 205 0.0036 Example 25 18 114 126 189 0.0027Example 26 18 114 125 165 0.0024 Example 27 16 114 121 160 0.0023Example 28 16 114 115 155 0.0023 Example 29 −8 114 97 667 0.0043Comparative 72 74 73 281 0.0046 Example 1 Comparative 57 102 86 10310.0067 Example 2 Comparative 52 110 85 2121 0.0065 Example 3 Comparative24 114 82 245 0.0068 Example 4 Comparative 20 114 — — — Example 5Comparative 24 114 125 110 0.0120 Example 6 Comparative 26 114 121 3200.0160 Example 7 Comparative 6 114 81 215 0.0065 Example 8 Comparative−14 114 58 523 0.0086 Example 9 Comparative 38 122 92 877 0.0067 Example10 Comparative 28 126 95 916 0.0055 Example 11 Comparative 12 126 84 9460.0048 Example 12

The results of table 3 will be described.

In Comparative Example 1, the value of “x” is 0.140, which is greaterthan 0.130. The results were as follows. The piezoelectric constant d₃₁at room temperature (25° C.) was 73, which was smaller than those ofExamples 1 to 29.

Further, in Comparative Example 12, the value of “x” is 0.015, which issmaller than 0.020. The results were as follows. The piezoelectricconstant d₃₁ at room temperature (25° C.) was 84, which was smaller thanthose of Examples 1 to 29.

In Comparative Example 4, the value of “a” is smaller than 0.9860. Theresults were as follows. The average equivalent circular diameter was15.1 μm, which was larger than those of Examples 1 to 29, and abnormalgrain growth occurred. The mechanical strength of the element wasevaluated by a three-point bending test, using a tension-compressiontest apparatus (trade name: Tensilon RTC-1250A, manufactured by OrientecCo., Ltd.). As a result, the mechanical strength of the element ofComparative Example 4 was 25 MPa, which was significantly lower thanthose of the piezoelectric elements of Examples 1 to 29, which were 45MPa or more.

In Comparative Example 5, the value of “a” is greater than 1.0200. Theresults were as follows. The grain growth was excessively suppressed ascompared to Examples 1 to 29, and the relative density was low, namely92.2%. As a result, the resistivity of the element of ComparativeExample 5 was low. Thus, a sufficient electric field was not able to beapplied to the element, and the element was not able to be subjected toa polarization treatment.

In Comparative Example 6, the amount of the contained Mn is 0.001 moles,which is smaller than 0.002 moles. The results were as follows. Themechanical quality factor Qm was 110, which was smaller than those ofExamples 1 to 29. As a result, when the element was driven as aresonance device, the power consumption increased.

In Comparative Example 7, the amount of the contained Mn is 0.018 moles,which is greater than 0.015 moles. The results were as follows. Thedielectric loss tangent was 0.0160, which was greater than those ofExamples 1 to 29, which were smaller than 0.006. As a result, when theelement was driven as a resonance device, the power consumptionincreased.

In Comparative Example 8, the amount of the contained Bi is 0.00040moles, which is smaller than 0.00042 moles. The results were as follows.The piezoelectric constant d₃₁ was 81 pm/V, which was smaller than thoseof Examples 1 to 29. Further, the dielectric loss tangent was 0.0065,which was greater than those of Examples 1 to 29, which were smallerthan 0.006. As a result, when the element was driven as a resonancedevice, the power consumption increased.

In Comparative Example 9, the amount of the contained Bi is 0.00900moles, which is greater than 0.00850 moles. The results were as follows.The piezoelectric constant d₃₁ was 58 pm/V, which was smaller than thoseof Examples 1 to 29. The dielectric loss tangent was 0.0086, which wasgreater than those of Examples 1 to 29, which were smaller than 0.006.As a result, when the element was driven as a resonance device, thepower consumption increased.

In each of Comparative Examples 2, 3, 10, and 11, the amount of thecontained Bi is 0 moles (that is, below the detection limit). Theresults were as follows. The respective piezoelectric constants d₃₁ were86 pm/V, 85 pm/V, 92 pm/V, and 95 pm/V. The respective phase transitiontemperatures T_(to) were 57° C., 52° C., 38° C., and 28° C.

The above four Comparative Examples 2, 3, 10, and 11 and among theexamples, those clearly different from the Comparative Examples 2, 3,10, and 11 for compositional reasons are comparatively considered.

As compared to Comparative Example 2, in Example 2, the phase transitiontemperature T_(to) is almost equal to that of Comparative Example 2, andthe amount of the contained Mn is 0.010 moles. Then, in Example 2, thepiezoelectric constant d₃₁ is 105 pm/V, which is 20% or more greaterthan the value of the piezoelectric constant d₃₁ of Comparative Example2, namely 86 pm/V.

Further, as compared to Comparative Example 3, in Example 3, the phasetransition temperature T_(to) is almost equal to that of ComparativeExample 3, and the amount of the contained Mn is 0.010 moles. Then, inExample 3, the piezoelectric constant d₃₁ is 95 pm/V, which is 10% ormore greater than that of Comparative Example 3, namely 85 pm/V.

Further, as compared to Comparative Example 10, in Example 4, the phasetransition temperature T_(to) is almost equal to that of ComparativeExample 10, and the amount of the contained Mn is 0.010 moles. Then, inExample 4, the piezoelectric constant d₃₁ is 119 pm/V, which is 20% ormore greater than that of Comparative Example 10, namely 92 pm/V.

Further, as compared to Comparative Example 11, in Example 5, the phasetransition temperature T_(to) is almost equal to that of ComparativeExample 11, and the amount of the contained Mn is 0.010 moles. Then, inExample 5, the piezoelectric constant d₃₁ is 128 pm/V, which is 20% ormore greater than that of Comparative Example 11, namely 95 pm/V.

The amount of the contained Mn is a parameter affecting the mechanicalquality factor Qm of the piezoelectric material. Generally, it is saidthat the mechanical quality factor Qm and the piezoelectric constanthave a trade-off relationship. Thus, when the piezoelectric propertiesare compared, the values of the mechanical quality factors Qm may beapproximated to some extent. It was understood that if, with this pointin mind, the piezoelectric properties were compared under the conditionsthat the amounts of the contained Mn were equal and the phase transitiontemperatures T_(to) were almost equal, the piezoelectric constant d₃₁ ofa sample containing Bi increased near room temperature.

In Example 13, the total amount of the contained Si and B is 0.0005parts by weight, which is smaller than 0.001 parts by weight. Theresults were as follows. The state of sintering was insufficient at amaximum sintering temperature T_(max) of 1200° C. and 1250° C. Thus, themaximum sintering temperature T_(max) required 1350° C. At this time,the relative density was high, namely 98.7%, and the piezoelectricconstant d₃₁ was great, namely 148 pm/V.

In Example 15, the total amount of the contained Si and B is 5.000 partsby weight, which is greater than 4.000 parts by weight. The results wereas follows. The state of sintering was insufficient at a maximumsintering temperature T_(max) of 1200° C. and 1250° C. Thus, the maximumsintering temperature T_(max) required 1300° C. At this time, therelative density was high, namely 98.6%, and the piezoelectric constantd₃₁ was great, namely 142 pm/V.

Further, Comparative Examples 6 and 7 demonstrated high piezoelectricproperties among the comparative examples. Then, in each of ComparativeExamples 6 and 7, the dielectric loss tangent was great, namely 0.008 ormore. As a result, when the element was driven as a resonance device,the power consumption increased. Thus, the element was not able to beapplied in terms of practicality.

(Production and Evaluation of Multilayered Piezoelectric Element)

Next, the multilayered piezoelectric element according to the presentinvention was produced.

Example 30

Raw materials corresponding to a composition(Ba_(0.9955)(Ti_(0.9960)Zr_(0.040))O₃), which is represented by thegeneral formula (1) of Ba_(a)(Ti_(1-x)Zr_(x))O₃, where x=0.040 anda=0.9955, were weighed in the following manner.

Raw material powders of barium titanate having a purity of 99.99% ormore and barium zirconate having a purity of 99.99% or more wereprepared as the raw materials of the main component and weighed so thatthe proportions of Ba, Ti, and Zr resulted in the compositionBa_(0.9955)(Ti_(0.9960)Zr_(0.040))O₃. Further, barium carbonate andtitanium oxide were used to adjust “a” indicating the ratio of the molaramount of Ba at the A site to the molar amounts of Ti and Zr at the Bsite.

Manganese dioxide was weighed so that the amount of an Mn elementcontained as the first auxiliary component was 0.002 moles relative to 1mole of the composition (Ba_(0.9955) (Ti_(0.9960)Zr_(0.040))O₃).

Bismuth oxide was weighed so that the amount of a Bi element containedas the second auxiliary component was 0.00200 moles relative to 1 moleof the composition (Ba_(0.9955) (Ti_(0.9960)Zr_(0.040))O₃).

Silicon dioxide was weighed so that as one of the third auxiliarycomponents, Si was 0.0670 parts by weight in terms of metal relative to100 parts by weight of the composition (Ba_(0.9955)(Ti_(0.9960)Zr_(0.040))O₃). Boron oxide was weighed so that as one ofthe third auxiliary components, B was 0.0330 parts by weight in terms ofmetal relative to 100 parts by weight of the composition(Ba_(0.9955)(Ti_(0.9960)Zr_(0.040))O₃).

PVB was added to and mixed with these weighed powders. Then, the mixturewas formed into a sheet by a doctor blade method, thereby obtaining agreen sheet having a thickness of 50 μm.

A conductive paste for internal electrodes was printed on the greensheet. As the conductive paste, a 70% Ag—30% Pd alloy (Ag/Pd=2.33) pastewas used. Nine green sheets to which the conductive paste was appliedwere stacked together, and the resulting laminate was sintered for 4hours under the condition of 1200° C. to obtain a sintered body.

The composition of a piezoelectric material portion of the thus obtainedsintered body was evaluated by an ICP emission spectroscopic analysis.As a result, it was understood that the piezoelectric material includedas the main component a metal oxide that can be represented by achemical formula Ba_(0.9955)(Ti_(0.9960)Zr_(0.040))O₃, and 0.002 molesof the Mn element and 0.00200 moles of the Bi element were containedrelative to 1 mole of the main component. Further, it was alsounderstood that 0.00670 parts by weight of Si and 0.00330 parts byweight of B were contained relative to 100 parts by weight of the maincomponent. The weighed composition of Ba, Ti, Zr, Mn, Bi, Si, and Bcoincided with the composition after the sintering.

The sintered body was cut into a size of 10 mm×2.5 mm, and then, theside surfaces of the cut sintered body were polished. A pair of externalelectrodes (a first electrode and a second electrode) for alternatelyshort-circuiting internal electrodes was formed by Au sputtering,thereby producing a multilayered piezoelectric element as illustrated inFIG. 2B.

The multilayered piezoelectric element includes nine piezoelectricmaterial layers and eight internal electrode layers. When the internalelectrodes of the obtained multilayered piezoelectric element wereobserved, electrode materials containing Ag—Pd were formed alternatelywith the piezoelectric materials.

A polarization treatment was performed on a sample prior to theevaluation of the piezoelectric properties. Specifically, the sample washeated to 100° C. to 150° C. on a hot plate, an electric field of 14kV/cm was applied to between the first and second electrodes for 30minutes, and after the sample was cooled to room temperature whileretaining the electric field, the application of the electric field wasended.

When the piezoelectric properties of the obtained multilayeredpiezoelectric element were evaluated, it was understood that even withthe multilayered structure, the multilayered piezoelectric element hadinsulation properties and piezoelectric properties equivalent to thoseof the ceramic of Example 17.

Further, also regarding a multilayered piezoelectric element producedsimilarly except that Ni and Cu were used for internal electrodes andthe multilayered piezoelectric element was sintered in a low-oxygenatmosphere, equivalent piezoelectric properties were obtained.

Comparative Example 13

A multilayered piezoelectric element was produced by processes similarto those of Example 30. However, the composition was similar to that ofComparative Example 11, the sintering temperature was 1200° C., andinternal electrodes contained a 95% Ag-5% Pd alloy (Ag/Pd=19). Theinternal electrodes were observed using an SEM. As a result, theinternal electrodes were melted and dotted in an insular manner. Thus,there was no electrical continuity between the internal electrodes, andtherefore, the multilayered piezoelectric element was not able to bepolarized. Consequently, the piezoelectric properties were not able tobe evaluated.

Comparative Example 14

A multilayered piezoelectric element was produced similarly toComparative Example 13 except that internal electrodes contained a 5%Ag-95% Pd alloy (Ag/Pd=0.05). The internal electrodes were observedusing an SEM. Peeling was found at the boundary between an electrodematerial containing Ag—Pd and a piezoelectric material layer. When themultilayered piezoelectric element was polarized, a sufficient electricfield was not able to be applied, and therefore, the multilayeredpiezoelectric element was not able to be polarized. Consequently, thepiezoelectric properties were not able to be evaluated.

Example 31

A liquid discharge head as illustrated in FIGS. 3A and 3B was producedusing the piezoelectric element including the piezoelectric material ofExample 20. The discharge of ink according to an input electric signalwas confirmed.

Example 32

A liquid discharge apparatus as illustrated in FIG. 4 was produced usingthe liquid discharge head of Example 31. The discharge of ink accordingto an input electric signal was confirmed on an object.

Example 33

An ultrasonic motor as illustrated in FIG. 6A was produced using thepiezoelectric element including the piezoelectric material of Example20. The rotation of the motor according to the application of analternating voltage was confirmed.

Example 34

An optical device as illustrated in FIGS. 7A and 7B was produced usingthe ultrasonic motor of Example 33. An autofocus operation according tothe application of an alternating voltage was confirmed.

Example 35

A dust removing device as illustrated in FIGS. 9A and 9B was producedusing the piezoelectric element including the piezoelectric material ofExample 20. When plastic beads were scattered and an alternating voltagewas applied, an excellent dust removing efficiency was confirmed.

Example 36

An imaging apparatus as illustrated in FIG. 12 was produced using thedust removing device of Example 35. When the imaging apparatus wasoperated, dust on the surface of the imaging unit was removedeffectively, and an image without dust defects was obtained.

Example 37

An electronic device as illustrated in FIG. 14 was produced using thepiezoelectric element formed of the piezoelectric material of Example20. A loudspeaker operation according to the application of analternating voltage was confirmed.

Example 38

A liquid discharge head as illustrated in FIGS. 3A and 3B was producedusing the multilayered piezoelectric element of Example 30. Thedischarge of ink according to an input electric signal was confirmed.

Example 39

A liquid discharge apparatus as illustrated in FIG. 4 was produced usingthe liquid discharge head of Example 38. The discharge of ink accordingto an input electric signal was confirmed on an object.

Example 40

An ultrasonic motor as illustrated in FIG. 6B was produced using themultilayered piezoelectric element of Example 30. The rotation of themotor according to the application of an alternating voltage wasconfirmed.

Example 41

An optical device as illustrated in FIGS. 7A and 7B was produced usingthe ultrasonic motor of Example 40. An autofocus operation according tothe application of an alternating voltage was confirmed.

Example 42

A dust removing device as illustrated in FIGS. 9A and 9B was producedusing the multilayered piezoelectric element of Example 30. When plasticbeads were scattered and an alternating voltage was applied, anexcellent dust removing efficiency was confirmed.

Example 43

An imaging apparatus as illustrated in FIG. 12 was produced using thedust removing device of Example 42. When the imaging apparatus wasoperated, dust on the surface of the imaging unit was removedeffectively, and an image without dust defects was obtained.

Example 44

An electronic device illustrated in FIG. 14 was produced using themultilayered piezoelectric element of Example 30. A loudspeakeroperation according to the application of an alternating voltage wasconfirmed.

The piezoelectric material according to the present invention hasexcellent piezoelectric properties in the room temperature range.Further, the piezoelectric material does not contain lead, and thereforehas little environmental load. Thus, the piezoelectric materialaccording to the present invention can be used without any problem evenfor a device using many piezoelectric materials, such as a liquiddischarge head, an ultrasonic motor, or a dust removing device.

According to an exemplary embodiment of the present invention, it ispossible to provide a lead-free piezoelectric material having moreexcellent piezoelectric properties in the room temperature range.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2014-113121 filed May 30, 2014, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A piezoelectric material comprising: a perovskitemetal oxide represented by following general formula (1); Mn; and atrivalent Bi, wherein an amount of the Mn is 0.0020 moles or more and0.0150 moles or less relative to 1 mole of the metal oxide, and anamount of the Bi is 0.00042 moles or more and 0.00850 moles or lessrelative to 1 mole of the metal oxideBa_(a)(Ti_(1-x)Zr_(x))O₃  (1) where 0.02≤x≤0.13 and 0.986≤a≤1.02, andwherein a relative density of the piezoelectric material is 93% or moreand 100% or less.
 2. The piezoelectric material according to claim 1,further comprising at least one of Si and B, wherein an amount of the atleast one of Si and B is 0.001 parts by weight or more and 4.000 partsby weight or less in terms of metal relative to 100 parts by weight ofthe perovskite metal oxide represented by the general formula (1). 3.The piezoelectric material according to claim 1, wherein atetragonal-orthorhombic phase transition temperature T_(to) is 10° C. ormore.
 4. The piezoelectric material according to claim 1, wherein anaverage equivalent circular diameter of crystal grains forming thepiezoelectric material is 500 nm or more and 10 μm or less.
 5. Thepiezoelectric material according to claim 1, wherein a dielectric losstangent, at a frequency of 1 kHz, of the piezoelectric material is 0.006or less.
 6. A piezoelectric element comprising: a first electrode; apiezoelectric material portion; and a second electrode, wherein apiezoelectric material of the piezoelectric material portion includes: aperovskite metal oxide represented by following general formula (1); Mn;and Bi, wherein an amount of the Mn is 0.0020 moles or more and 0.0150moles or less relative to 1 mole of the metal oxide, and an amount ofthe Bi is 0.00042 moles or more and 0.00850 moles or less relative to 1mole of the metal oxideBa_(a)(Ti_(1-x)Zr_(x))O₃  (1) where 0.02≤x≤0.13 and 0.986≤a≤1.02.
 7. Amethod for manufacturing a piezoelectric element, the method comprising:providing the piezoelectric material according to claim 1 with a firstelectrode and a second electrode; applying a voltage at a temperature atwhich the piezoelectric material becomes tetragonal; and cooling thepiezoelectric material to a temperature at which the piezoelectricmaterial becomes orthorhombic, while retaining the voltage.
 8. Thepiezoelectric element according to claim 6, further comprising aplurality of piezoelectric material layers including the piezoelectricmaterial portion and a plurality of electrode layers including the firstelectrode and the second electrode electrode, the piezoelectric materiallayers and the electrode layers being alternately stacked.
 9. Thepiezoelectric element according to claim 8, wherein the plurality ofelectrode layers includes an internal electrode containing Ag and Pd,and wherein a weight ratio of M1/M2 is 0.25 M1/M2≤4.0 where a weight ofthe contained Ag is M1 and a weight of the contained Pd is M2.
 10. Thepiezoelectric element according to claim 8, wherein the plurality ofelectrode layers includes an internal electrode containing at least oneof Ni and Cu.
 11. A liquid discharge head comprising: a liquid chamberincluding a vibrating unit provided with the piezoelectric elementaccording to claim 6; and a discharge port communicating with the liquidchamber.
 12. A liquid discharge apparatus comprising: a stage for anobject; and the liquid discharge head according to claim
 11. 13. Anultrasonic motor comprising at least: a vibrating member provided withthe piezoelectric element according to claim 6; and a moving member incontact with the vibrating member.
 14. An optical device comprising adriving unit provided with the ultrasonic motor according to claim 13.15. An oscillatory device comprising a vibrating member including adiaphragm provided with the piezoelectric element according to claim 6.16. A dust removing device comprising a vibrating unit provided with theoscillatory device according to claim
 15. 17. An imaging apparatuscomprising at least: the dust removing device according to claim 16; andan image sensor unit, wherein the diaphragm of the dust removing deviceis provided on a light-receiving surface side of the image sensor unit.18. An electronic device comprising a piezoelectric acoustic componentprovided with the piezoelectric element according to claim
 6. 19. Thepiezoelectric material according to claim 1, wherein the piezoelectricmaterial contains 90 mole percent of the metal oxide as a maincomponent.
 20. The piezoelectric material according to claim 19, whereinthe piezoelectric material contains 95 mole percent of the metal oxideas the main component.
 21. The piezoelectric element according to claim6, wherein the Bi is trivalent Bi.